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GAO: Questions remain about composite jets like Boeing 787

U.S. and European regulators followed procedures in certifying Boeing’s mostly composite 787 Dreamliner aircraft and took steps to address potential safety concerns, but it’s too soon to say whether these steps are enough, Congressional auditors reported Thursday (pdf).

“It is too early to fully assess the adequacy of FAA and industry efforts to address safety-related concerns and to build sufficient capacity to handle and oversee composite maintenance and repair, given that composite airframe structures in currently in-service airplanes are mostly limited to the secondary structures,” Gerald Dillingham, directors of Physical Infrastructure Issues at the Government Accountability Office, wrote in a report requested by the top Democrats on the U.S. House of Representatives Committee on Science, Space, and Technology, that committee’s Subcommittee on Investigations and Oversight and the Aviation Subcommittee of the Committee on Transportation and Infrastructure.

Boeing’s 787 and the competing Airbus A350 XWB are about half composites, up significantly from other airliners, which use aluminum for the fuselage skin and wings.

While composites are lighter and stronger than most metals, the GAO wrote: “Some industry observers have raised concerns about the state of the science underpinning the expanded use of composite materials in commercial transport category airplanes and FAA’s preparedness for this transition.”

Responding to the report Thursday, Boeing said it “is pleased that the GAO report demonstrated confidence in the FAA and in the process through which the FAA certifies the safety of commercial airplanes,” adding:

Regardless of the materials we use, Boeing employs the same rigorous methods to deliver products that are safe for the flying public and efficient for airlines. We test, we analyze and we demonstrate to ourselves and to the regulatory agencies that even in extreme conditions — which may never be experienced in a full life of service — the airplane is safe and durable.

As the GAO report points out, composite materials have been used in commercial airplanes for decades. The concerns in the GAO report are limited to support activities (repair and maintenance). These issues already are being addressed through an industry-wide effort involving regulators, manufacturers, operators and maintenance and repair organizations. This is a great example of how all stakeholders work together to ensure safety continues at today’s high levels.

The Boeing 787 Dreamliner is about half composites. (U.S. Government Accountability Office)

For instance, fuselage damage may be less visible on a composite aircraft and, therefore, go undetected. People have also raised concerns that a composite fuselage would break up in a more-dangerous way during a crash, that a fire would release toxic fumes and that composites are more vulnerable to lightning.

The GAO noted that the FAA imposed five special conditions “where it determined the applicable airworthiness regulations did not contain adequate or appropriate safety standards for design features related to the 787’s composite fuselage and wings.”

The conditions required Boeing to show that:

The composite fuselage is resistant to flame spreading and that flames don’t cause hazardous fumes;

The 787, in crashes at up to 30 feet per second, provides equivalent protection as similar aluminum airliners;

Tire debris will not penetrate, deform or crack the wing fuel tanks, and that hazardous amounts of fuel would not enter specific areas of the plane and engine;

The 787 wings and fuel tanks can endure an external fuel-fed fire on the ground for at least five minutes when the fuel tanks contain various levels of fuel;

Lightning is extremely unlikely to ignite a fuel tank and the aircraft includes all practical measures to prevent, detect and correct failures of lightning-protection features.

EASA imposed five similar conditions, adding to the post-crash fire-resistance requirement a stipulation that Boeing provide safety information for rescue crews. It also imposed conditions related to fuel tank flammability and lightning protection; and required more information about the performance of composites where the tail attaches to the fuselage, and protection from tire, wheel and engine debris.

Congressional auditors said concerns remain in four areas:

Limited information on the behavior of composite airframe structures;

Technical challenges in detecting and fixing damage to composites materials;

Limited standardization of composite materials and repair techniques; and

The level of training and awareness on composites.

To address these issues, the FAA has updated guidance and proposed new guidance related to composites, and is conducting research, developing and implementing training for inspectors and working with companies, which are continuing to research composites, the GAO reported. It’s too soon to say whether that’s enough, auditors wrote.

As more airlines add airplanes with composite fuselages and wings, the FAA will probably need to certify and oversee more composite repair facilities, the GAO said, adding that it’s too soon to gauge the extend of this demand or how well the FAA is positioned to meet it.

Finally, the FAA’s ability to ensure safety of composite aircraft depends on how it addresses broader issues auditors have previously uncovered, including lack of proper oversight of airlines and repair stations, auditors wrote. “(T)he increased use of composite materials in airplanes may exacerbate some of these weaknesses — and their associated risks — if FAA does not take appropriate corrective steps.”

Note: This is a seattlepi.com reader blog. It is not written or edited by the P-I. The authors are solely responsible for content. E-mail us at newmedia@seattlepi.com if you consider a post inappropriate.